Genes encoding the T cell antigen receptor have been studied using the rabbit T cell line RL-5. Cloned cDNA corresponding to both alpha and beta chains of the T cell receptor has been obtained. The sequence of a full-length beta chain clone of 1.3 kb in length which includes the V, D, J and C region has been determined. A second cDNA clone of approximately 1 kb from RL-5 is presently under study. Two distinct clones corresponding to the alpha genes were identified in the RL-5 cDNA library using a murine alpha chain probe and analysis is underway. A restriction fragment length polymorphism (RFLP) of the beta chain genes was observed using the enzyme EcoRI on Southern blot analysis. Family studies using this RFLP have determined that the beta genes are autosomal, that they have no linkage to the heavy chain gene complex and that there is a possible linkage to the k light chain gene complex. Studies of the beta genes in a genomic library have revealed the presence of two C beta genes located about 7 kb apart. The full-length cDNA transcript corresponds to the 3 prime C beta gene and therefore, it is the homolog of C beta 2 in the mouse and human. Structural comparisons of rabbit beta chain genes reveal 75% protein homology to mouse and human and about 80% nucleic acid homology. The rabbit V region sequence, by contrast, has only 14-23% homology to reported human and murine sequences.